Begonias are popular ornamental plants. The short answer to whether they can be planted outside is yes, but with a distinct seasonal qualification in most regions. These tropical and subtropical plants are extremely sensitive to cold and frost, meaning they are generally treated as warm-season annuals in temperate climates, providing continuous color from late spring until the first frost. In warmer USDA Zones 9 through 11, many begonia varieties can survive the winter outdoors and function as true perennials.
Which Begonia Varieties Thrive Outside
The suitability of a begonia for outdoor planting depends heavily on its root structure, which classifies it into different types. Wax begonias (Begonia semperflorens), also known as fibrous begonias, are the most common choice for outdoor garden beds and mass plantings. These varieties are resilient, offering a compact, uniform look with continuous small flowers and waxy green or bronze foliage. They are almost exclusively grown as annual bedding plants outside of frost-free regions.
Tuberous begonias (Begonia tuberhybrida) are prized for their spectacular, large, camellia-like blossoms, often used in containers or hanging baskets. These grow from a fleshy, underground tuber and are highly sensitive to cold. In most climates, their tubers must be dug up and stored indoors for the winter.
Cane begonias, including popular types like Dragon Wing and Angel Wing, have upright, cane-like stems and are usually kept in containers. While they are often moved outdoors for the summer, they must be brought inside before cold weather arrives to be overwintered as houseplants.
Optimal Timing and Placement
Begonias should only be moved outside after the last expected frost date has passed. Nighttime temperatures must consistently remain above 50°F (10°C) before planting them directly into the ground or containers.
Begonias generally flourish in bright, indirect light or filtered shade, replicating their native tropical understory environment. Direct afternoon sun, especially in hot climates, can easily scorch the leaves and stunt growth. Varieties with darker foliage can tolerate slightly more sun exposure.
The soil must be rich and well-draining. Begonias are highly susceptible to root rot if they sit in overly wet conditions.
Transitioning and Planting Outdoors
Before transplanting begonias grown indoors or in a greenhouse, they must be gradually acclimated to the outdoor environment through “hardening off.” This transition should take place over seven to ten days, slowly exposing the plants to increasing sunlight, wind, and fluctuating temperatures.
Start by placing the plants in a shaded, sheltered outdoor spot for one to two hours on the first day, bringing them back inside each night. Each day, progressively increase the duration of their outdoor exposure and the amount of light they receive until they can handle a full day outside.
When planting, amend the garden soil with organic matter like compost to improve drainage and fertility. Begonias should be planted at the same depth they were in their containers. Adequate spacing allows for air circulation, which helps prevent common fungal diseases.
Routine Summer Care
Once established, begonias require consistent maintenance to support their extended blooming period. The soil should be kept uniformly moist, but never waterlogged; check the top inch of soil before watering again. Always direct the water at the base of the plant to keep the foliage dry, as wet leaves increase the risk of fungal issues like powdery mildew.
Since begonias are heavy feeders, a regular fertilization schedule is necessary to maintain continuous flowering. Apply a balanced, water-soluble fertilizer every two to three weeks, or use a high-phosphorus formula to encourage more abundant blooms.
Monitor the plants for common garden pests such as slugs and snails. Remove spent flowers to encourage the plant to put energy into producing new buds.
End-of-Season Winterizing
As temperatures begin to drop, most outdoor begonias need preparation for the cold months. Fibrous and wax begonias are typically treated as true annuals in zones below USDA 9 and are removed from the garden after the first hard frost.
The tubers of tuberous begonias can be saved by lifting them from the soil after the foliage naturally yellows and dies back, usually following the first light frost. After digging, cut the stems back, clean the tubers by gently removing excess soil, and allow them to dry or “cure” in a warm, dry place for several days.
Once dried, store the firm, intact tubers in a cool, dark, and frost-free location, such as a basement or garage. Use a breathable medium like peat moss or vermiculite, maintaining a temperature between 40°F and 50°F (4°C and 10°C). Potted cane varieties should be brought indoors before the first frost and treated as houseplants in a bright location, receiving reduced watering until spring.